Automakers are committing vital sources to develop electrical, autonomous, and hybrid automobiles. These OEMs additionally want to satisfy rising demand for better connectivity in each class of automotive, together with automobiles with inside combustion engines. Automotive lightweighting, a design technique that seeks to scale back automobile weight, isn’t new. It has, nevertheless changing into extra necessary for causes past gasoline effectivity and emissions reductions. Right now, engineers need light-weight supplies that enhance design, manufacturability, and the efficiency of molded and machined components.
For many years, automotive designers have been changing heavier metallic elements with engineering plastics and fiber-filled composite variations. This observe is now broadening as automakers look past exterior elements and inside fixtures. Due to advances in polymer expertise, engineers have a wider vary of latest and lighter choices for drivetrain and underhood elements. Importantly, these supplies supply better design freedom and slot in effectively with the lightweighting methods that transcend changing metallic with plastic.
This complicated 10-port water outlet made from Solvay’s heat-stabilized polyphthalamide (PPA) resists water and glycol at 135°C for five,000 hours. The fabric saved 25% in prices and virtually a pound in weight in comparison with a metallic model, and its pull-pass barb molding functionality diminished the variety of components.
Designers who take a system-level strategy in all automotive segments are discovering new potentialities. For instance, the distinctive mixture of superior polymers’ properties are enhancing the slot liners and magnet wire insulation in electrical (EVs), hybrid electrical (HEVs), and plug-in hybrid electrical automobiles (PHEVs). In flip, non-metal supplies cut back the load and dimension of traction motors whereas enhancing their effectivity. In all kinds of vehicles, changing a number of metallic components with a single plastic half reduces automobile weight whereas lowering the quantity of meeting wanted.
Current advances in polymers let automotive designers contemplate completely different manufacturing strategies. Most moldable components are injection molded, however plastic coolant tubing is extruded, thermoformed, and spin welded onto connectors. Plastic thermoforming additionally makes exterior elements comparable to hoods and spoilers. As well as, superior polymers work effectively with adhesives and could be machined from inventory shapes or printed by way of additive manufacturing (aka 3D printing) throughout prototyping. Plastic composites with vital glass, mineral, or carbon fiber content material could be precision machined with tight tolerances.
Automotive designers might admire the design flexibility and manufacturing advantages superior polymers present, however excessive temperatures and publicity to chemical compounds or fluids would possibly make metals look like the one alternative for particularly demanding purposes. This isn’t the case, nevertheless, as demonstrated by latest improvements in polymers for automotive electrical techniques and electronics, inside combustion engines, gasoline injection techniques and assemblies, transmissions, EV batteries and cooling, and electrified drivetrains.
These newer supplies would possibly look like simply the most recent chapter within the historical past of automotive lightweighting, however polymers aren’t simply changing metals. They’re changing different plastics, too. When choosing supplies, then, designers have to suppose past plastics vs. metals and examine the efficiency profiles of high-performance specialty polymers.
Spider graphs like this one let designers examine and distinction traits of associated supplies. This one seems at polyphthalamide (PPA), polyamide 66 (PA66), and polyphenylene sulfide (PPS).
Plastics in Automobiles
In Plastics and Polymer Composites in Gentle Automobiles, a report from the American Chemistry Council, the trade commerce affiliation explains that in 1960, the common gentle automobile contained simply 20 lb of plastics and polymer composites. By 1990, this had climbed to 191 lb, and by 2018, non-metal supplies averaged 342 lb for eight.6% of complete automobile weight. Right now, plastics usually make up 50% of the amount of a light-weight automobile however lower than 10% of its weight.
For the reason that 1960s, plastics have modified auto physique designs and let OEMs undertake modular meeting practices whereas reducing manufacturing prices. Plastic components for automotive interiors promoted not solely consolation and styling, but additionally ergonomics and noise management. When automotive consumers grew to become extra involved about auto security, plastics had been added to door modules to strengthen side-impact resistance and plastic foams added to automotive cavities to extend occupant security and diminished noise, vibration, and harshness (NVH).
Right now, automotive plastics are used with brake pistons, wheel velocity sensors, and components such because the solenoids and plungers within the hydraulic management models of anti-lock brakes. Automotive plastics within the chassis present energy and rigidity whereas absorbing vitality that may trigger NVH. As well as, specialty polymers are utilized in powertrains, which embody the interior combustion engines, batteries, and motors.
Many automotive gasoline techniques and engine elements additionally use plastics as an alternative of metallic. Over the past a number of a long time, in truth, plastics have helped remodel automotive electrical techniques. For instance, plastic elements help the operation, interconnection, and housing of printed circuit boards, connectors, sockets, switches, wires, and cables. As laptop chips regulate and monitor automotive subsystems, specialty polymers could be discovered in all the things from international positioning techniques for navigation to audio techniques for leisure.
Right now’s vehicles comprise electrical and digital elements that carry out many necessary capabilities, however sensors are particularly vital. As an illustration, anti-lock brake sensors monitor wheel velocity, oxygen sensors decide how a lot gasoline is required to run the engine effectively, and different sensors monitor coolant ranges. Superior polymers help these and different automotive sensors whereas withstanding the excessive temperatures and harsh environments related to such techniques.
As automotive electronics turn out to be smaller and extra densely packaged, superior polymers have began to switch extra conventional engineering ones comparable to commonplace polyamides. For instance, Solvay produces a polyphthalamide (PPA) that gives a sexy stability of properties in comparison with polyamide 66 (PA66) and polyphenylene sulfide (PPS). PPA maintains its properties in humid environments, affords superior dimensional and thermal stability, and gives better resistance to a broad vary of chemical compounds, together with brake fluid.
Superior polymers additionally enhance fluid monitoring in electrified drivetrains. A few of these supplies are inherently warmth secure and don’t require components to inhibit or forestall thermal degradation. There are additionally polymers with non-metal warmth stabilizers that may forestall thermal degradation if wanted. For instance, Solvay’s PPA incorporates an natural stabilizer that’s freed from migrating metallic that would short-circuit an electrical system.
Designers depend on superior PPS in automobile electrical techniques and electronics purposes as a result of they’ve long-term resistance to temperatures as much as 392°F (200°C) and short-term resistance to temperatures as much as 500°F (260°C). PPS affords the broadest resistance to chemical compounds of any high-performance plastic and might mix dimensional stability and inherent flame retardancy with help for precision molding to tight tolerances with excessive reproducibility. With its mixture of properties, PPS is a wonderful candidate for electrical and digital elements in coolant techniques and for oil and gasoline system elements.
Specialty polymers, comparable to Solvay’s high-performance polyetheretherketones (PEEK), are sometimes specified for electrical water and oil pumps. They cut back weight whereas providing wonderful chemical resistance for sturdy, long-term efficiency. In addition they have dimensional stability wanted for tight tolerances that may preserve excessive pumping efficiencies.
Gas injector O-rings made out of Solvay’s fluoroelastomers (FKM) supply good efficiency in sealing purposes for aggressive chemical and high-heat environments. The fabric additionally has a large operational temperature vary and stays versatile even at sub-zero temperatures.
Superior polymers can now be present in ducts and sensors for turbochargers and superchargers. As a result of these gadgets should face up to excessive temperatures and corrosive exhaust gases, they want supplies that resists each. Fluoroelastomers (FKM) can join ducts on the new sides of superchargers and turbochargers. Along with reducing weight, FKM helps manufacturability and has low-temperature capabilities. For decent-side air ducts in high-temperature diesel purposes, PPS is used.
One other space for weight discount is fluid dealing with tubes. For instance, PPS extrusion grades are considerably lighter than the costlier metallic/rubber coolant traces. PPS is effectively fitted to versatile tubing with diameters from eight to 22 mm with wall part thickness from 1 to 1.7 mm. These are utilized in post-extrusion thermoforming, a course of that seems gadgets with predefined shapes from heated supplies.
As a metal-replacement materials, PPS displays excessive soften energy and thermal stability, together with enhanced tensile and influence energy. In contrast to metallic tubes, specialised grades of extruded PPS don’t require coating as a result of they resist highway salt, oil, gasoline, and different chemical compounds. Together with its lighter weight and chemical resistance, PPS additionally has wonderful thermal resistance, making it a sensible choice for connectors and brackets in sizzling, cramped engine bays. In some designs, PPS additionally helps eradicate warmth shields. And brackets could be overmolded onto the tubing to make a whole meeting.
Oil pump housings additionally make good use of superior polymers. Historically, these elements consisted of light-weight aluminum. Nevertheless, designers now have polymers for much more weight discount and a greater stability of mechanical properties beneath high-temperatures and pressures. Solvay’s 30% carbon-fiber-reinforced polyaryletherketone (PAEK) compound can meet these calls for and is stiffer than PEEK at 150°C to 200°C. This high-end PAEK additionally has wonderful machinability and fatigue resistance.
Cam sprockets are one other space for specialty polymers. In inside combustion engines, these chain-driven sprockets connect to at least one finish of the cam shaft and, together with the timing belt, assist to take care of correct timing for optimum engine efficiency. But cam sprockets are additionally uncovered to excessive torque, excessive temperatures, vibration, filth, automotive fluids, and highway salt. If these components overheat, chip, lose their form, or fail to carry out reliably beneath load, the engine timing received’t work correctly.
Most cam sprockets are made from sintered metal or aluminum, however some are made out of thermoset phenolic polymers. A substitute for all these supplies is polyamide-imide (PAI). Solvay’s PAI supplies ship the very best energy, stiffness, and fatigue resistance of all thermoplastics at temperatures as much as 525°F (274°C). It has a selected energy of 5.four x 105 in-lbf/lb (1.four 105 J/kg) and a selected stiffness 6 x 107 in-lbf/lb (15 106 J/kg). Against this, chrome steel delivers a selected energy and stiffness of three.1 x 107 in-lbf/lb (Zero.eight 106 J/kg), and 9.7 x 107 in-lbf/lb (24 106 J/kg), respectively.
Superior polymers additionally supply benefits for the design, manufacture and efficiency of fuel-handling elements. Their lighter weight helps elevated gasoline effectivity, however plastics that resist rupture and supply excessive influence energy additionally forestall gasoline supply techniques from leaking or corroding. However as engine pressures and temperatures proceed to extend, designers want next-generation metallic replacements to face up to demanding circumstances whereas performing constantly in all environments and climates.
Gas rails, the high-pressure tubing that sends gasoline to injector nozzles, are historically made from metal. If there is no such thing as a gasoline injection, nevertheless, plastic fuels rails can be utilized. PPA and PPS bolstered resins resist alcohol-based fuels at excessive temperatures and pressures. These glass-fiber bolstered compounds add dimensional stability and let gasoline rails be injection molded as a single piece. Against this, conventional metallic rails are usually six-part welded metal assemblies.
For gasoline injection assemblies, FKM could be fabricated into O-rings with wonderful sealing drive and gasoline compatibility at excessive temperatures whereas remaining versatile. Solvay’s peroxide-curable FKM grades supply the bottom cold-temperature efficiency and finest gasoline compatibility amongst all fluoroelastomers. Extra particularly, the fabric’s glass transition (Tg) temperature of −40°F (−40°) helps be sure that O-rings in high-performance engines carry out reliably inside design limits even beneath excessive stress.
In standard automobiles, the grasp cylinder converts drive into hydraulic stress and controls slave cylinders that disengage the clutch from the engine. In a twin concentric slave cylinder (DCSC), sealing rings should face up to excessive hundreds every time a automotive shifts gear. Traditionally, sealing rings have been both aluminum or engineering polymers. Right now, specialty lightweight polymers present higher put on resistance and dimensional stability.
Excessive efficiency PAI lets DCSC seal rings guarantee constant contact with the cylinder’s chamber partitions, which minimizes friction and ensures cleanliness in a transmission’s high-cycle, high-pressure setting. This polymer makes for tight, sturdy seals that allow the DCSC function constantly no matter fixed publicity to filth, mud, particles, transmission fluids, and temperatures biking between −40°F and 320°F (−40°C and 160°C).
PAIs will also be made into locking gadgets that maintains exact radial positions throughout the DCSC all through the transmission’s life. This specialty polymer contributes little friction and displays extraordinarily low put on. Its wonderful lubricity and fatigue resistance additionally lets the locking system face up to hundreds of thousands of loading cycles from the clutch.
Thrust washers, one other transmission part, also can use PAI due to its efficiency in dry and lubricated environments because of its wonderful put on resistance and dimensional stability at elevated temperatures and pressures. It additionally resists creep and chemical compounds, together with sturdy acids and most organics. All this makes it effectively fitted to extreme service environments with prolonged efficiency necessities.
Water pump impellers made from Solvay’s polyphenylene sulfide (PPS), resist water/glycol at 140°C for five,000 hr. Versatile extruded coolant traces made out of PPS can substitute heavier, more-expensive metallic/rubber cooling traces, be used for extra complicated routing in cramped engine bays, and eradicate the necessity for warmth shielding.
Light-weight metals comparable to aluminum are utilized in many EV batteries. They resist burning and defend in opposition to electromagnetic interference (EMI), a rising problem for purposes with densely packaged electronics. Metals additionally present reliable mechanical and dimensional properties, however they arrive with trade-offs. In comparison with a battery pack the place just a few components are plastic, the all-metal unit weighs considerably extra.
To interchange metallic components, automotive designers have turned to superior polymers for electrical insulation that received’t compromise EV batteries’ mechanical and dimensional properties. When making components, specialty polymers supply decrease preliminary mold-shrink and warpage tolerances. In addition they have decrease moisture absorption for dimensional stability and are available UL 94 V-Zero grades for flame resistance.
For battery direct-immersion cooling, superior perfluoropolyethers (PFPE) present excessive thermal stability, a variety of working temperatures, good dielectric properties, and wonderful chemical inertness. This fluorinated heat-transfer fluid is effectively fitted to battery packs’ liquid coolant because it has no flash or fireplace level. PFPE can be suitable with commonplace metals and plastics; maintains secure properties over time; and reduces the chance of quick circuits, corrosion, and cross-contamination.
Specialty polymers that decrease the load of vehicles and vans are additionally lowering NVH in electrical automobiles. As extra individuals drive EVs, engineers have to silence noises that wouldn’t be heard over the sound of a fuel engine. Plus, EVs shut down their engines when stopped however don’t shut off varied followers that whirl and whine. As a result of light-weight plastics in lots of EVs are extra prone to vibration, superior specialty polymers are getting used to reduce or eradicate NVH.
In EVs, pumps are sometimes additionally electrical and should carry out beneath the frequent cease/begin circumstances simply talked about, which introduces better friction and put on. As a result of fluids used with these pumps have a comparatively low viscosity, lubrication is a matter. New ultra-low viscosity (ULV) transmission fluids are extra energy-efficient however lack the lubricity some pump designers anticipate. For bushings and bearings on this higher-friction setting, elements made out of high-performance PEEK thermoplastics can do the trick.
Different superior polymers suitable with ULV transmission fluids embody a number of grades of Solvay’s PPS. They work with UL 25 transmission fluid and have been evaluated beneath ISO and ASTM strategies to measure modifications in mechanical properties. These supplies are crammed with completely different percentages of glass fiber and exhibit minimal modifications to tensile energy and elongation.
Transmission thrust washers and seal rings made from Solvay’s polyamide-imide (PAI) carry out effectively in dry and lubricated environments, because of the fabric’s put on resistance and dimensional stability.
The Highway Forward
Right now, many vehicle designers are searching for new methods to scale back automobile weight utilizing plastics and plastic composites. They’re additionally contemplating methods to switch plastic and composite components with superior, higher-performing polymers that meet extra demanding necessities or comprise low-density components, various fibers and nanoparticles. Superior polymers are utilized in all vehicles and vans and elevated security necessities and self-driving vehicles present much more alternatives.
By taking an general strategy as an alternative of merely changing metals with plastics, engineers can cut back the load of automobiles, enhance efficiency and security, and achieve better design freedom. It additionally reduces meeting occasions and prices by lowering half counts. Whether or not the way forward for the auto is hybrid, electrical, autonomous, or one thing else, superior polymers will play an necessary function.
Sandra McClelland is gross sales growth manager-NAFTA Automotive at Solvay’s Specialty Polymers enterprise unit. Mark Wright is international automotive market supervisor for Solvay’s Specialty Polymers and Composite Supplies enterprise models. For extra info on superior polymers go to Solvay.com or e-mail [email protected] or [email protected].